if 5>12:
    print("5 is greater than 2")
    print("2222222")
else:
    print("5 is not greater than 12")

    age = 30
    if age < 18:
        print("you are underaged") # &&不可用
    elif age >= 18 and age < 30:
        print("you are young")
    elif age >= 30 and age <50:
        print("you are middle-aged")
    else:
        print("you are old")

    # ctrl + d 复制一行
    # ctrl + alt + L 格式化代码
     #判断闰年
    year = int(input("请输入年份："))
    if (year % 4 == 0 and year % 100 !=0) or (year % 400 ==0):
        print("%d是闰年" % year)
    else:
        print("%d不是闰年" % year)

    # a b c 比较大小
    a = int(input("请输入a:"))
    b = int(input("请输入b:"))
    c = int(input("请输入c:"))
    if a>b:
         if a>c:
                print("a is the largest")
         else:
                print("c is the largest")
    else:
        if b>c:
                print("b is the largest")
        else:
                print("c is the largest")


    #计数器实现加减乘除
    num1 = float(input("请输入第一个数字："))
    num2 = float(input("请输入第二个数字："))
    op = input("请输入运算符：")
    if op == "+":
        print(num1 + num2)
    elif op == "-":
        print(num1 - num2)
    elif op =="*":
        print(num1 * num2)
    elif op =="/":
        print(num1 /num2)
    else:
        print("输入错误")
